Vertically staggered pallet stacking assembly line and method

Abstract

A pallet stacking assembly line having at least two pick-and-place robots are used. The first robot has a relatively low position. The second robot is in an elevated position. A pallet dispenser dispenses a first pallet onto a pallet conveyor The pallet conveyor moves the first pallet to a first build position in front of the first robot. The first robot picks products from a first pick position and stacks them on the first pallet. Once the stack of products on the first pallet reach approximately half the finished stack height, the pallet conveyor carries the first pallet to a second build position in front of the second robot. At the same time, the pallet dispenser dispenses a second pallet which is carried to the first build position. The second robot picks products from a second pick position and places them on the upper portion of the stack on the first pallet to complete the stack. Meanwhile, the first robot is picking and placing products on the lower portion of the second pallet. The process continues indexing, with both robots ideally being busy all the time. Each robot builds half the stack on the pallet,

1 . An assembly line for stacking products on pallets to a specified total height, comprising:
 a. a pallet conveyor having a conveyor path direction, including
 i. a first build position, 
 ii. a second build position downstream of the first build position in the conveyor path direction; 
   b. a pallet supply adjacent the conveyor, including an elevator for sequentially placing a plurality of pallets onto said pallet conveyor;   c. a product supply device supplying a plurality of products to be stacked on said pallets, wherein the product supply is offset in a horizontal direction from the pallet conveyor;   d. a first robot, located proximate said first build position and positioned on a first base at a low elevation so that the range of motion of said first robot encompasses said product supply and said first build position up to an elevation greater than one half of said specified total height of said pallets, said first robot configured to pick up a first product selected from said plurality of products from said product supply, transport said first product from said product supply to said first build position, and deposit said first product on one of said pallets; and   e. a second robot, located proximate said second build and positioned on a second base which elevates the second robot higher than first base elevates the first robot, wherein the second base is at a high elevation, so that said range of motion of said second robot encompasses said product supply and said second build position up to an elevation greater than said specified total height of said pallets, said second robot configured to pick up a second product selected from said plurality of products from said product supply, transport said second product from said product supply to said second build position, and deposit said second product on one of said pallets.   
   
   
       2 . An assembly line as recited in  claim 1 , wherein said product supply includes a product conveyor. 
   
   
       3 . An assembly line as recited in  claim 2 , wherein said product conveyor further comprises:
 a. a first pick position located proximate said first robot; and   b. a second pick position located proximate said second robot.   
   
   
       4 . An assembly line as recited in  claim 2 , wherein said first pick position is at said low elevation and said second pick position is at said high elevation. 
   
   
       5 . An assembly line as recited in  claim 1 , wherein said product supply comprises:
 a. a first product conveyor supplying said products to a first pick position located proximate said first robot; and   b. a second product conveyor supplying said products to a second pick position located proximate said second robot.   
   
   
       6 . An assembly line as recited in  claim 5 , wherein said first pick position is at a low elevation and said second pick position is at a high elevation. 
   
   
       7 . An assembly line for stacking products on pallets to a specified total height, comprising:
 a. a pallet conveyor having a conveyor path direction, including
 i. a first build position, 
 ii. a second build position downstream of the first build position in the conveyor path direction, 
 iii. a third build position downstream of the first build position in the conveyor path direction; 
   b. a pallet supply device adjacent the pallet conveyor and placing a plurality of pallets onto said pallet conveyor;   c. product supply capable of supplying a plurality of products to be stacked on said pallets, wherein the product supply is offset in a horizontal direction from the pallet conveyor;   d. a first robot, located proximate said first build position, wherein said first robot is on a first base at a low elevation so that the range of motion of said first robot encompasses said product supply and said first build position up to an elevation greater than one third of said specified total height of said pallets, aid first robot configured to pick up a first product selected from said plurality of products from said product supply, transport said first product from said product supply to said first build position, and deposit said first product on one of said pallets;   e. a third robot, located proximate said third build position, wherein said third robot is on a third base at a high elevation, so that said range of motion of said third robot encompasses said product supply and said third build position up to an elevation greater than said specified total height of said pallets, said third robot configured to pick up a third product selected from said plurality of products from said product supply, transport said third product from said product supply to said third build position, and deposit said third product on one of said pallets; and   f. a second robot, located proximate said second build position, wherein said second robot is on a second base at an elevation between said elevation of said first base and said elevation of said third base, so that said range of motion of said second robot encompasses said product supply and said second build position at an elevation less than one third of said specified total height of said pallets and greater than two thirds of said specified total height of said pallets, said second robot configured to pick up a second product selected from said plurality of products from said product supply, transport said second product from said product supply to said second build position, and deposit said second product on one of said pallets.   
   
   
       8 . An assembly line as recited in  claim 7 , wherein said product supply comprises a product conveyor. 
   
   
       9 . An assembly line as recited in  claim 8 , wherein said product conveyor further comprises:
 a. a first pick position located proximate said first robot;   b. a second pick position located proximate said second robot; and   c. a third pick position located proximate said third robot.   
   
   
       10 . An assembly line as recited in  claim 7 , wherein said product supply comprises:
 a. a first product conveyor supplying said products to a first pick position located proximate said first robot;   b. a second product conveyor supplying said products to a second pick position located proximate said second robot; and   c. a third product conveyor supplying said products to a third pick position located proximate said third robot.   
   
   
       11 . An assembly line as recited in  claim 9 , wherein:
 a. said first robot is located atop the first base which comprises a first robot pedestal;   b. said second robot is located atop the second base which comprises a second robot pedestal;   c. said third robot is located atop the third base which comprises a third robot pedestal;   d. said product conveyor passes beneath said third robot and through said third robot pedestal;   e. said product conveyor passes beneath said second robot and through said second robot pedestal; and   f. said product conveyor passes beneath said first robot and through said first robot pedestal.   
   
   
       12 . A method of stacking products on pallets to a specified total height, comprising:
 a. providing an assembly line, including
 i. a pallet conveyor, including
 1. a first build position, 
 2. a second build position downstream of the first build position in a pallet conveying direction of the conveyor, 
 
 ii. pallet supply, capable of placing a plurality of pallets onto said pallet conveyor, 
 iii. product supply capable of supplying a plurality of products to be stacked on said pallets, wherein the product supply is offset in a horizontal direction from the pallet conveyor; 
 iv. a first pick-and-place robot, located proximate said first build position and on a first base at a low elevation so that the range of motion of said first robot encompasses said product supply and said first build position up to an elevation greater than one half of said specified total height of said pallets, 
 v. a second pick-and-place robot, located proximate said second build position and on a second base at a high elevation, so that said range of motion of said second robot encompasses said product supply and said second build position up to an elevation greater than said specified total height of said pallets; 
   b. actuating said pallet supply to place a first pallet on said pallet conveyor;   c. actuating said pallet conveyor in order to move said first pallet to said first build position;   d. actuating said first robot to pick up, transport, and stack said products on said first pallet up to approximately one half of said specified total height; e. actuating said pallet supply to place a second pallet on said pallet conveyor;   e. actuating said pallet conveyor to move said first pallet to said second build position and said second pallet to said first build position;   f. actuating said second robot to stack said products on said first pallet up to said specified total height; and   g. at approximately the same time, actuating said first robot to stack said products on said second pallet up to approximately one half of said specified total height.   
   
   
       13 . A method as recited in  claim 12 , wherein said product supply comprises a product conveyor. 
   
   
       14 . A method as recited in  claim 13 , wherein said product conveyor further comprises:
 a. a first pick position located proximate said first robot; and   b. a second pick position located proximate said second robot.   
   
   
       15 . A method as recited in  claim 12 , wherein said product supply comprises:
 a. a first product conveyor supplying said products to a first pick position located proximate said first robot; and   b. a second product conveyor supplying said products to a second pick position located proximate said second robot.   
   
   
       16 . A method as recited in  claim 14 , wherein:
 a. said first robot is located atop the first base which comprises a first robot pedestal;   b. said second robot is located atop the second base which comprises a second robot pedestal;   c. said product conveyor passes beneath said second robot and through said second robot pedestal; and   d. said product conveyor passes beneath said first robot and through said first robot pedestal.   
   
   
       17 . A method as recited in  claim 16 , wherein:
 a. said product conveyor feeds said products first to said second pick position and then to said first pick position; and   b. said second pick position includes a through-feed gate which controls the flow of said products to said first pick position.   
   
   
       18 . A method as recited in  claim 16 , wherein:
 a. said product conveyor feeds said products first to said first pick position and then to said second pick position; and   b. said first pick position includes a through-feed gate which controls the flow of said products to said second pick position.   
   
   
       19 . A palletizer for stacking products on pallets, said palletizer comprising:
 a pallet conveyor having a conveyor path direction, including at least a first build position and a second build position downstream of the first build position in the conveyor path direction;   a pallet loader adjacent the conveyor, wherein the loader places pallets sequentially on said pallet conveyor;   a product conveyor having a first product conveyor section adjacent the first build position of the pallet conveyor and a second product conveyor section adjacent the second build position of the pallet conveyor, wherein the product conveyor is offset in a horizontal direction from the pallet conveyor such that the first product conveyor section and second product conveyor section do not overlap in a vertical direction the pallet conveyor;   a first robot proximate said first build position and having a range of motion encompassing said first product conveyor section and said first build position, wherein the first robot is mounted on a first pedestal at a first elevation above the first conveyor section and said first robot is configured to pick up and lift a first product from said first product conveyor section, transport said first product to said first build position, and deposit said first product a pallet at the first build location, and   a second robot proximate said second build position and having a range of motion encompassing said second product conveyor section and said second build position, wherein the second robot is mounted on a second pedestal at a second elevation above the first elevation and above the second conveyor section, and said second robot is configured to pick up and lift a second product from said second product conveyor section, transport said second product to said second build position, and deposit said second product the first product previously deposited on the pallet, wherein the pallet has been moved to the second build location by the pallet conveyor.   
   
   
       20 . The palletizer in  claim 19  wherein the first conveyor section is at an elevation no higher than an elevation of the second conveyor section, and the elevation of the second conveyor section is above the first elevation of the pedestal for the first robot. 
   
   
       21 . The palletizer in  claim 20  wherein the elevation of the second conveyor section is above the surface of the product conveyor. 
   
   
       22 . A method of stacking products on pallets to a specified total height, comprising:
 placing a pallet on a pallet conveyor;   at a first build position, transporting product from a first product supply position to the pallet on the pallet conveyor, wherein the first product supply position does not overlap in a vertical direction the pallet conveyor and wherein a first robot picks up and lifts the product from the first product supply position and moves the product to the pallet and places the product on the pallet, and wherein the first robot is mounted on a first pedestal at a low elevation no higher than an upper elevation of the product placed on the pallet at the first build position;   advancing the pallet on the pallet conveyor from the first build position to a second build position, where the second build position is horizontally spaced from and downstream along the conveyor from the first build position, and   at the second position, transporting product from a second product supply position to the pallet on the pallet conveyor, wherein the second product supply position does not overlap in a vertical direction the pallet conveyor and wherein a second robot picks up and lifts the product from the second product supply position, moves the product to the pallet and places the product on the product placed on the pallet at the second build position, wherein the second robot is mounted on a second pedestal at an upper elevation above the low elevation and no higher than an upper elevation of the product placed on the pallet at the second build position.   
   
   
       23 . The method of  claim 22  further comprising:
 positioning the first product supply position at an elevation below the pallet conveyor at the first build position, and   positioning the second product supply position above the elevation of the first product supply position and above the elevation of the pallet conveyor at the second build position.